The present invention relates generally to telecommunications, and more particularly to enhancing the scalability of an Internet Protocol (IP) Multimedia Subsystem (IMS) in Voice over IP (VoIP), Service over IP (SoIP), and the like, deployment.
IP Multimedia Subsystem (IMS), in theory, is a traffic-independent scalable architecture. Various Session Initiation Protocol (SIP) servers can be deployed dynamically to users and such servers are distributed such that the capacity is extensible. However, SIP is a text-based signaling protocol and has a large message size. In some instances, the SIP response message may exceed that allowed for User Datagram Protocol (UDP), which is typically the underlying protocol for layer 3 (i.e. the network layer of the Open Systems Interconnection (OSI) reference model), thereby causing the fragmentation of the response message. Due to the large message size combined with the typical large number of SIP nodes/servers in IMS, a large number of messages are produced and complicated message flows must be processed, all of which reduces the scalability of IMS in, for example, an enterprise/business VoIP deployment. In addition, it should be noted that the 3rd Generation Partnership Project (3GPP) (standard TS-23.228 V8.8.0. (2009-03) IMS System Architecture) does not specify how Quality of Service (QoS) within IMS is realized.
Setting up a multimedia communication session in IMS conventionally involves a two round procedure as shown in FIGS. 2 and 3. In a first round, shown in FIG. 2, a signal path is determined from a calling party to a called party. In a second round, shown in FIG. 3, resources for supporting the communication are negotiated and reserved. As illustrated by FIGS. 2 and 3, each request to initiate a communications session requires multiple SIP messages to be transmitted. The number of messages transmitted as shown in FIGS. 2 and 3 multiplied by the number of communications sessions requested typically results in a large number of SIP messages transmitted which often results in messages being truncated and/or lost during transmission. What is needed is a way to initiate communications sessions with less signaling messages.